In recent years, so-called electronic markets where many virtual stores are set up over the Internet are becoming more common. In electronic markets, each store creates and posts a sales page for each product, and through this sales page, a customer purchases a desired product.
Such electronic markets are quite often designed to provide, when a store creates the sales page, a so-called category name to a product. By having the products categorized with category names, stores can systematically manage many products, and customers can compare products belonging to the same category through a single search, and thus this is convenient.
For example, Patent Literature 1 discloses a product transaction system that stores, for each search database corresponding to a category name, specification information of the product with the category name in association with an ordinary everyday expression describing features of the product.